Process of producing cyanogen compounds



JOHN COLLINS OLANCY, OF FREEPORT, NEW YORK, ASSIGNOR TO THE NITROGEN CORPORATION, OF PR0VIICENCE, RHODE ISLAND, A' CORPORATION OF RHODE ISLAND.

No Drawing.

To all whom it may concern:

Be it known that I, JOHN COLLINS CLANCY, a citizen of the United States, residing at F reeport, in the county of Nassau and State of New York, have invented certain new and useful Improvements in Proccsses of Producing Cyanogen Compounds, of which the following is a specification.

This invention relates to an improved process of producing substantially pure cyanogen compounds and derivatives thereof;

and more especially concerns a cyclic method essential ingredients in of fixing nitrogen preferably in the form of an alkali metal cyanid.

As is well known, attempts, extending over a period of more than seventy years, have been made to effect the fixation of nitrogen economically in the form of cyanogen compounds, and while it was for a long time suspected that it might be possible to fix free nitrogen in the form of alkali cyanid in such a manner as to warrant the commercial development of such a process,'

owing to a non-recognition of important factors involving the provision of a suitable catalytic agent in the solid phase and the disposition of the latter with respect to other the charge in such fashion as to permit of a satisfactory yield of the product sought, together with the vital maintenance of the essential conditions after they were once established, to effect a really satisfactory and copious formation of such product at a reasonably low temperature, there followed, one after another during this long term of years, a series of practically abortive attempts to solve the problem. The practical failure of these at-' tempts is evidenced by their failure of commercial development, despite the great need of a nitrogen fixation process which could very cheaply convert free nitrogen into such a product as would be substantially at once available for use without further costly treatment after its formation.

The first recognition of the factors aforesai 'l.certainl v at least in their entirety and in such fashion as to make them apparent to those skilled in the art, occurs in the patents to John E. Butcher, and notably those numbered 1,0 1.42?) and 1,120,682 and respectively dated March 24. 191-1 ber 17 1 H. These Bucher processes have Specification of Letters Patent.

able retort, heated and Deceni PROCESS OF PRODUCING CYANOGEN COMPOUNDS.

i Patented Feb. 3, 1920.

Application filed June 12, 1917. Serial No. 174,377.

come into extensive commercial use and in one of its principal aspects, the hereindescribed process or method may be regarded as a further development of this art thus made practicable by said Bucher.

As set forth in the aforesaid Patent No. 1,091,425, cyanid of sodium, for example, may be made at a comparatively low temperature by thoroughly mixing together, in the manner described in said patent, sodium carbonate, pulverulent coke or charcoal and preferably very finely divided iron. The mixture may be used in powdered form or it may be formed into porous briquets; preferably in accordance with the disclosur in the Bucher Patent N 0. 1,120,682.

Upon passing hot nitrogen gas or even producer gas through this mixture, in a suitto, for example, a red heat or bright red heat, the alkali metal, which forms the base of the carbonate or its equivalent, is combined with the nitrogen and with carbon from the catalyzer, to form alkali metal cyanid; the reaction being represented thus:

(1) Na CO, +40 +N +iron 2N aCN 300 +iron.

Obviously, other alkali-base supplying compounds than the carbonates are available; as for example the hydrates, bicarbonates, etc. Also, as is pointed out in the said Bucher patents, various catalyzers are adapted for use in the process; but iron is to be preferred, principally, on account of its cheapness.

In view of the very full disclosures in said patents to John E. Bucher, for brevity herein, it is obvious that the various equivalents of substances,such as graphite, carbon-supplying gases, c. 9., varioushydrocarbons, etc., for the above mentioned powdered coke or charcoal; producer gas, etc., as a source of free nitrogen; not alone iron, but manganese, nickel, etc., or mixtures or compounds of these, as catalyzers;need not be further referred to herein.

The reactive mass, either in pulverulent form, or, preferably, in the form of porous catalytic briquets. as aforesaid-after subjection to nitrogen during the proper heat etreatinent to prevent sintering. of the catalyzer, or flooding of the reactive carbon-supplying catalytic SUJI'fHCG in the pores .of sai briquets,-is, as described in the Bucher atents, efliciently cyanized; a very considerable proportion of the carbonate, or other source of the alkali metal, being converted to alkali metal cyanid; or, by regulation of the supply of carbon, in a known manner, to, for example, alkali metal cyanamid.

After the so cyanized charge has been cooled, it has been customary in practice to liXiviate it with water to dissolveout the cyanid; but right here was encountered a difficulty which has been the source of trouble and expense. In operating the Bucher processes, while in theory, or on a comparatively small scale, substantially a quantitative conversion of carbonate, for example, to cyanid was possible,-in practice and on a large scale the conversion could be by no means complete; so that there is almost inevitably, under such conditions, a remnant of the carbonate intimately associated with cyanid in the mass, and when the latter is lixiviated with water this residual carbonate or the like goes into solution along with the cyanid and contaminates the.

latter.

What is still worse, from several points of view, is that the metal catalyzer is attacked and if this be iron, as preferred, ferrocyanid of the alkali metal is formed and this also goes into the solution.

Thus impure cyanid is produced, when operating con'nnercially, and, further, there is a loss of catalytic material; not to mention an impairment of that which is left when the residues have been re-pulverized preparatory to re-use in the process.

Furthermore, the liXiviationhas to be long continued to effect a satisfactory recovery of cyanid from the mass, which itself is costly; while an aqueous solution of the impure product is formed, involving a prolonged and costly drying operation.

My problem then was the Bucher processes in question, so as to render the whole, in effect, cyclic,by winning the cyanid from the cyanized charge or mass without destroying or impairing the catalyzer, and preferably without dissolving out the carbonate, or its equivalent, or forming or dissolving out already formed contaminating by-products. It was also aimed to eliminate the costly liXiviation with water and the subsequent tedious treatment of theaqueous solution.

This problem I have solved and the various difficulties aforesaid have been completely overcome by my discovery of a solvent for alkali metal cyanids which is wholly incapable of attacking the iron, nickel, manganese or equivalent catalyzer, either to dissolve the same, or to oxidize,

and chlorate.

presence of some water vapor,

to further develop Lemma or pounds therewith; while, furthermore, said solvent possesses practically no solvent action upon the alkali metal carbonates, or other preferred sources of the base of the cyanogen compound to be formed as per said Bucher processes, or upon any of the solid icy-products incident thereto.

-This action is the more peculiar since while an alkali metal cyanid may be dissolved in liquid ammonia, solvent preferred, the alkaline-earth metal cyanids cannot. On the other hand the alkali metal cyanamids and cyanates are thus soluble in this reagent; as arealso, forexample, sodium chlorid, sulfid, hypochlorite Further, it is somewhat remarkable that while barium cyanid, for example, is insoluble in liquid ammonia, barium chlorid, contrawise, is soluble; and hile nickel in the metallic state is unaffected by this agent,-nickel chlorid, niclkel acetate, etc, are soluble. Similarly, cad mium-chlorid, for example, is also soluble; as are, too, zinc chlorid, manganese chlorid and many other salts.

When the'Bucher processes described in said patents numbered 1,091,425 and 1,120,682 are followed up to the stage where the charge has become well cyanized,not only will there be sodium carbonate, for example, present in the reaction residues; but there also may be present, when operating commercially, sodium oxid and sodium hydrate, the latter probably as a result of the either formed during the course of the operation or initially present either in the charge or in the gases supplied to the latter.

Here again the ammoniacal solvent discloses its peculiar value in connection with said processes, since even these impurities are all substantially insoluble in it; with the result that when the said reaction residues are treated With ammonia in the manner hereinafter described,-an alkali metal cyanid is obtained which is indeed remarkable for its purity; being almost chemically pure. Carbon, it may be added, is of course, insoluble in liquid ammonia.

While the solvent action of ammonia upon the alkali metal cyanids has been known, or suspected, for nearly twenty years, this compound seems not to have been. available for commercial production of the product sought probably on account of the fact that chlorids and sulfids are, as above pointed out, so soluble in it that the obtaining of an uncontaminated product by means thereof was rendered prohibitively costly.

Thus, in the British patent to Craig, No. 11,912 of 1900, there is a disclosure of the use of l quid ammonia in'the obtainment of cyanid; but the reaction residues, which anotherwise form a compound or com.

which is the duction of no described in this patent as being treated with this reagent, are not those resulting from a cyanid forming reaction; "but on the contrary, thecrude cakereferred to in said patent, must first be treated to, at least in theory, render-the injurious soluble impurities, insoluble in liquefied ammonia.

That this treatment appears to have been successful in practice does not satisfactorily appear, while from the fact that it is not today in commercial use, in spite of the demand for pure cyanid, raises a strong presumption, in view of the lapse of time, that this process was not a practicable one.

On the other hand, in the present process, there is the special relationship between the cyanid producing step of the process, per 86, and the step of at once recovering pure product from the reaction mass, which has enabled the production of alkali cyanid cheaply and in large quantities; while said present process owes much of its efficiency to its cyclic character; there being no waste of material, catalytic or otherwise; nor prolonged lixiviation of the cyanized reaction products required.

In brief the present process preferably comprises the formation of the cyanid of an alkali metal, such as sodium, from a suit able compound of such metal, to wit, sodium carbonate,-which compound and all reaction products thereof, save the product sought, are wholly or very nearly completely insoluble in the ammoniacal reagent subse quently used. The cyanogen compound forming reaction i preferably effected at such a temperature as will afi'ord a copious yieldof said cyanogen compound without wastefully vaporizing the carbonate or the like and without impairing the finely divided catalyzer preferably employed.

As to the source of the carbon for the reacti0n,this is material principally in so far as the maintenance of an adequate supply of carbon to the catalyzer is concerned and further in that sulfur or like impurities,w'hich might result in the formation of soluble alkah compounds or the like,- are excluded.

The material iii which the cyanid or the like is to be formed is preferably briqueted, and here again the formation of the briquets should most preferably involve the introsulfur or the like.

It is for this reason that the procedure of said Bucher in using the insoluble carbonate or like salt, itself as thebinder for said bri uets is of reat value when inco 0-- rated as a step of the present process;

The step of cooling the cyanized briquets, as described in the Bucher Patent No. 1,120,682, also most advantageously knits into the steps of the herein described improvement; since, as the solvent in question is one that volatilizes at a relatively low su bjected,-preferably in hereinafter, there are still other residing in the treatment by liquid ammonia temperature, under normal pressure conditions, it could not be used to advantage upon a-hot mass.

The cyanized charge, sufficiently to prevent of said solvent and when therefore, is cooled undue evaporation sufliciently cool, is a receptacle distinct from theretort in which the cyanid or the like was formed,-to the selective solvent action of liquid ammonia; a-stream or quantity of the latterpreferably ibeing permitted to pass through or permeate the mass, to leach out the cyanid or the like therefrom.

In this connection it may be well to emphasize the importance of having the cooled cyanized material in a form which affords a multiplicity of interstices, extending substantially therethroughout, to the end that an actual stream of the liquid ammonia mav be passed through the mass, as aforesaid.

he liquid ammonia should permeate all parts of the material under treatment and, as the cyanid or the like goes very readily into solution in said ammonia, a practically saturated solution is speedily formed in any given part of the mass, if the liquid ammonia, is stagnant or idle, or nearly so.

Obviously if such saturated ammonia is not removed prior to the steps of draining and evaporating the solvent, then upon evaporation of the liquid cyanid will deposit out very nearly where it was when it went into solution.

here, however, the charge to be c'yanized is properly briqueted in accordance with the disclosure of said ferred to, and the briquet formation is, after cyanization, then utilized during the eX- traction step of the process, it is evident that said formation affords the desired interstices; so that monia can pass freely through it and the development of idle saturated masses of liquid ammonia is avoided.

As will be more specifically .pointed out advantages of a cyanized charge in the form of b-riquets, or the like.

The container for the mass to be leached -may be iron; but since the liquid ammonia possesses the ability to penetrate the pores of many cast iron receptacles, care must be exercised to either use a practically nonporous iron or the like, or to allow the pores of the latter to choke up with cyanid, for example, if waste of'the solvent is to be avoided.

The leached mass is then allowed to drain and may thereafter be gently heated to volatilize any remaining ammonia present therein; the gaseous ammonia any suitable manner for ultimate return to the process.

ammonia, thethe stream of liquid am- Biucher, herein'before rebeing collected in how quickly the residues and this especially the tedious drying It is surprising may be completely dried, when one bears in mind necessary after lixiviation, per the Bucher disclosures.

The dried residues are at once available for return to the process; being, especially if in briquet form, repulverized to have added thereto suflicient carbonate or the like and carbon to replace that converted into cyanid, if t atbe the product sough The catalyzer is wholly unaffected by the ammonia and its surface (or multitudinous surfaces) is unimpaired, while no loss thereof occurs as when aqueous lixiviating liquids are used.

A'bove all, also, no ferro-cyanid or the like is formed and the solvent contains practically nothing else but the cyanogen compound to the produced; While, further, this solvent reclaims practically all of the cyanid or the like, the percentage left in the residual mass being really negligible.

The cyanized solvent is, of'course, collected and is then preferably subjected to moderate heat to drive ofi the ammonia and leave the alkali cyanid, for example, as a white, finely divided mass of almost chemically pure crystals; much like granulated sugar in appeanance.

It is believed that this product is distinctively new, as it seems to possess the property of enteringinto solution in water with great ease, whereas, to the best of my knowledge, the alkali cyanid now on the market which is available for ore treating operations, dissolves in water quite slowly; and certainly very slowly as compared with the product aforesaid.

To return to the process, orated ammonia is of course conserve ing collected and recondensed preparatory to its further use in the process; air being preferably carefully excluded, from the ammonia circuit.

In fact it is mostdesirable to exclude air from the retort in which the cyanogen comd, be-

pound is formed and especially to preserve the cyanized mass from exposure to. any oxidizing agent unless the product, sought 1s cyanate; since when the mass of heated cyanized briquets, for example, is exposed to the air, cyanate Wlll form therein and this, as abovestated, .is soluble in the leaching agent. V L

After, the cyanized mass has been properly cooled, oxidation of the productdoes not readily occur; but even then, in order to save ammonia and insure purity of the product, air should be excluded as far as the entire operation" preferably airfrom the lent or briqueted the retort until the crystalline alkaline with water as contrary, they are moved.

proper, the evap does away with aftei' cyanid, or the like, is recovered from the ammonia.

When, as is to be preferred, the charge is in briqueted form, a further advantage is derived from the ammonia treatment subsequent to cyanization and in combination therewith; since the briquets after such treatment,- having parted with'their cyanid content,are not,as one might at first think would be the case,-rendered shapeless or more or less plastic orfragile; but,-to the found to have become quite hard and brick-like; so that they may be dropped from a moderate height without breaking, and are hence, subsequently, more readily handled.

Their appearance also seems to be modified by subjection to the ammoniabath; as they become somewhat more. shiny or lustrous in appearance. This phenomenon seems to convey a'hint that some ammoniacal compound, possibly involving cyanogen, is formed; but if this be so, there is left in said briquets at most but a trace thereof, after 'the solvent has been completely re In conclusion, it should be observed that it is extremely desirable to use the same catalytic material, to wit, iron,-over and over again; since it has been found in practice that after it has been used as a catalyzer once or more, especially after treatmentas aforesaid, its condition for the purpose -1n-.

tended seems to be better than that of, for example, finely powdered iron which has 'never been so used or treated. The importance of using ammonia as a leaching reagent, in the process in question, rather than water, is hence additionally enhanced; there being no deleterious action thereof on the catalyzer, whatsoever, but rather, apparently, a beneficial one; and this in contradistinctionto the deleterious and destructive action of such a fluid as water, which forms hydrates of'iron, ferro-cyanids, etc. The step, too, of recovering the cyanid from the cyanized charge by means of liquid ammonia has the added advantage that the formation of the cyanid solution is not alone almost instantaneous, but it furthermore, is effected at room temperatures, or lower.

The low viates any necessity heat to the solvent or temperature of the operation obfor the application of to the charge at this llt) stage of the process and correspondingly the necessity for providing heating appliances, other than for the subsequent evaporation of the solvent; and even: this latteris vastly less'expensive than is the evaporation ofi of a large amount of water. Thus, for example, in removing the residual ammonia from the leached charge the latter has been drained as aforesaid, a gentle heat will in the course of half an hour render the mass practically perfectly dry. The evaporated ammonia is preferably, in every case, passed into a suitable refrigerating apparatus to effect recondensation thereof, preparatory to its return to the receptacle in which it may be stored until it is to be used for further leaching out of cyanid or the like, in the manner above described.

Finally, I may state that to the best of my knowledge, my invention, herein described, is the first to afford a practical nitrogen-fixation process in which pure cyanid of an alkali metal may be synthetically produced in a single heating operation, at a moderate temperature (red heat) adapted to conserve the life of the apparatus employed,-coupled with a simple, inexpensive and almost instantaneous selective leaching operation which does not impair the reaction residues and which when followed by the third step of evaporating the selective solvent off at a gentle 'heat(212 F, for example) yields the product sought in extraordinarily pure and finely divided condition.

Moreover, the reaction residue is in the best possible condition to be supplemented by fresh alkali compound and carbon for reuse in the process.

It is, too, believed that the present invention is the first catalytically-operating,

cyanid-forming process, in which the cataup under temperatures residues,

lyst, unimpaired, may be cyclically utilized, to form substantially uncontaminated cyanid, and as pointed out, in effect, in the said patents to John E. Bucher, unless a catalyst is used in the cyanid formation, the temperature requirements in so 'far as the conversion of such an inexpensive substance as soda ash, or sodium carbonate, into cyanid, are concerned,-become prohibitive for practical purposes on account of the-inability of the necessary apparatus to stand materially in excess of a bright red heat.

Electric furnaces intended to effect the direct synthetic formation of cyanid at upward of 1800 C. have been proposed; but so far as I am aware they exist only on paper.

Having thus described my invention, what I claim is: 1. The process of obtaining alkali metal cyanid, which comprises catalytically effecting a synthetic reaction, in which participate carbon, free nitrogen which constitutes the source of'the alkali metal base of the cyanid to be formed, the catalyst for said reaction beinga metal in finely divided condition, cooling the reaction and thereafter subjecting the products of said reaction, while, cool and intimately associated with said'catalyst, to the action of a solvent for said alkali cyanid which solvent is incapable of chemically reand a compound acting upon said catalyst to form any com pound therewith at the temperature of the operation, recovering said alkali cyanid in substantially pure condition from saidsolvent, and subjecting the remaining and undissolved residues, including said catalyst, to further participation in said reaction.

2. The process of obtaining alkali metal cyanid, which comprises catalytically efiecting a synthetic reaction, in which participate carbon, free nitrogen and a compound which constitutes the source of the alkali metal base of the cyanid to be formed, the catalyst for said reaction being ironin finely divided condition, cooling the reaction residues, and thereafter subjecting the products of said reaction, While cool and intimately associated with said catalyst, to the action of a solvent for said alkali cyanid which solvent is incapable of chemically reacting upon said iron catalyst to form any -compound therewith at the temperature of, the operation, recovering said alkali cyanid in substantially ure condition from said solvent, and sub ecting the remaining and undissolved residues, including said catalyst, to further participation in said reaction.

3. The process of obtaining an alkali metal cyanogen compound, which comprises forming a briqueted charge from a mixture of pulverulent'materials which includes a compound capable of acting as thesource of the alkali metal base of the cyan'ogencompound to be'formed, intimately mixed with a carbonaceous substances, the briquets of said charge being both firm and porous, cyanizing said briquets by heat treatment while subjecting them to the action of free nitrogen, cooling the still briqueted but now cyanized charge, and so separating the alkali metal cyanid therefrom as to leave said charge in briqueted form, by treating said charge with said cyanid, the briqueted form and porous condition of said charge favoring said separation.

4. The process of obtaining an alkali metal cyanogen compound, which comprises forming porous catalytic briquets by using as a binder for the catalytic material to be briqueted, an alkal'i'compound which constitutes-the source of the alkali metal of the cyanogen compound to be obtained, subjectsupplying carbon" and free nitrogen to the surface of said catalytic material exposed in the pores of said briquets, so conducting said treatment as to maintain said surface effective to cause the formation of said cyanogen compound through the chemical reaction of said alkali compound with said free nitrogen and. carbon cooling the briquets and separating therefrom the so formed cyanogen compound through the instrumentality of a substance which is ina selective extracting agent for rial therein.

free nitrogen and carbon,

'stantially only while maintaining the integrity of said bri- .briquets and leaving them 5. The process 'of obtaining an alkali metal cyanogen compound which comprises forming porous catalytic briquets by using as a binder for the catalytic material to be briqueted, an alkali compound which constitutes the source of the alkali metal of the cyanogen compound to be obtained, subjecting said briquets to heat treatment While supplying carbon and free nitrogen to the surface of said catalytic material exposed in the pores of said briquets, said treatment as to maintain said surface effective to cause the formation of said cyanogen compound through the chemical reaction of said alkali compound with said cooling the briquetsand separating therefrom the so formed cyanogen compound through the intermediacy of a substance which acts selectively upon the reaction products present in said briquets, to eliminate therefrom subsaid cyanogen compound,

quets and leaving them resistant to fracture.

6, The process of obtaining an alkali metal cyanogen compound, which comprises subjecting porous briquets to heat treatment to effect, within the pores of said briquets, a cyanogen compound forming reaction in which participate carbon, an alkali metal and free nitrogen, cooling said briquets, and separating the so formed cyanogen compound therefrom through the intermediacy of a substance which acts selectively u on the reaction products present in said riquets while maintaining the integrity of said ture, to facilitate their subsequent handling.

7. The process of obtaining an alkali metal cyanogen compound, which comprises catalytically effecting a reaction in which participate the elements carbon, an alkali metal, oxygen and free nitrogen, the products of said reaction including the alkali metal cyanogen compound to be obtained, intimately commingled with an oxid of said alkali metal, the catalyzer through the instrumentality of which said reaction was effected, a compound which constitutes the source of said alkali metal, and carbon, cooling the said reaction productswhile excluding air therefrom, and subjecting said cooled products to the action of ammonia.

8. The process of obtaining an alkali metal cyanogen compound, which comprises catalytically eifecting a' reaction in which participate the elements carbon, an alkali metal, oxygen and free nitrogen, the products of said reaction including the alkali metal cyanogen compound to be obtained intimately commingled with an oxid of said alkali metal, the catalyzer through the inso conducting iesistant to fracstrumentality of which said reaction was effected, a compound which constitutes the source of said alkali metal, and carbon, cooltially excluded, and recovering from said circuit the product sought.

9. The process of obtaining an alkali metal cyanogen compound, which comprises effecting a reaction in which participate the elements carbon, an alkali metal, oxygen and free nitrogen, the products of said reaction including the alkali metal cyanogen compound to be obtained, intimately commingled with an oxygen compound of said alkali metal and carbon, cooling the said reaction products, and subjecting them to the action of a stream of liquid ammonia while said products are in a form which affords interstices through the mass thereof, to extract said cyanogen compound, said interstices permitting access of said stream of liquid ammonia to substantially all parts of the material under treatment.

10. The process of obtaining an alkali metal cyanogen compound, which comprises eflecting a reaction n which participates the elements carbon, an alkali metal, oxygen and free nitrogen, the products of said reaction including the alkali metal cyanogen compound to be obtained, intimately commingled with an oxygen compound of said alkali metal and. carbon, cooling the said reaction products, and subjecting them'to the action of liquid ammonia while main taining through the mass tliereof a multiplicity of interstices of size and extent suflicient to insure free and rapid penetration of said liquid ammonia into substantially all parts of the material under treatment.

11. The process of obtaining an alkali metal cyanogen compound, which comprises effecting a reaction in which participate the elements carbon, an alkali metal, oxygen and free nitrogen, the products of said reaction including the alkali metal cyanogen compound to be obtained, intimately commingled with an oxygen compound of said alkali metal and carbon, cooling the said reaction products, and efiiciently extracting said cyanogen compound therefrom by efprises efiecting a reaction in which said compound is formed at a temperature sufiiciently high to at least partly fuse a carbonate of said alkali metal, While utilizing the fused carbonate in said reaction as the source of the alkali metal which forms the base of the cyanogen compound sought, said carbonate, just previous to its fusion as aforesail, being substantially free from Water, cooling the non-gaseous reaction residues to render all of them solid, treating said residues With-a non-aqueous solvent for said alkali cyanogen compound which is substantially incapable of chemically changing or dissolving any of the solid alkali carbonate which is present at such time in said residues, removing said solvent from the undissolved residues, with said cyanogen compound in solution therein, to leave said undissolved residues substantially dry, and returning to said process the residual alkali carbonate together with an additional quantity of said carbonate, to replace that consumed.

13. The process of producing a cyanogen compound of an alkali metal which comprises effecting a reaction in which said compound is formed at a temperature sutliciently high to at least partly :t'use a carbonate of said alkali metal, While utilizing the fused carbonate in said reaction as the source of the alkali metal Which forms the base of the cyanogen compound sought, said carbonate, just previous to its fusion as aforesaid, being substantially free from Water, cooling the non-gaseous reaction residues to render all of them solid, treating said residues With a non-aqueous solvent for said alkali cyanogen compound which is substantially incapable of chemically changing or dissolving any of the solid alkali carbonate which is present at such time in said residues, removing said solvent from the undissolved residues, with said cyanogen compound in solution therein, and returning to said process the residual alkali carbonate still mixed with the remaining reaction residues.

In testimony Whereof I have afiixed my signature in the presence of two WllSIlQSSBS.

JOHN COLLINS CLANCY. Witnesses a J. M. ARCHER, G. R. MORRIS. 

